Lab Matters Summer 2019 - Page 53

APHL 2019 POSTER ABSTRACTS Background: Foodborne Diseases Active Surveillance Network (FoodNet) conducts active laboratory-based surveillance for nine enteric pathogens in 10 sites. Use of culture-independent diagnostic tests (CIDTs) to diagnose enteric infections is increasing, including highly sensitive multiplex polymerase chain reaction (PCR)-based syndrome panels that can detect multiple pathogens from a single specimen. Detection of multiple pathogens that could be the cause of infection complicates case classification, cluster detection, and treatment decisions. We describe polymicrobial detections (PDs) and examine changes in their frequency. Methods: We analyzed 2011-2017 FoodNet data on PDs that included Campylobacter, Shiga toxin-producing Escherichia coli, Listeria, Salmonella, Shigella, Vibrio, Yersinia, Cryptosporidium, or Cyclospora. We defined a PD as detection of >1 pathogen, or >1 species or serotype by culture or CIDT in a single specimen or in specimens collected <30 days apart. FoodNet has collected reports of positive CIDTs for bacterial infections since 2012. We define a case as a laboratory-diagnosed infection; thus, PDs are reported as more than one case. Results: During 2011-2017, we identified 1,693 persons with a PD, resulting in 3,412 cases (2% of all cases reported to FoodNet). PDs were identified in specimens collected on the same day for 1,384 (82%) persons, within 1–7 days for 158 (9%) persons, and 8–30 days for 151 (9%) persons. Among patients with PDs, 1,523 (90%) had pathogens of two genera, 139 (8%) had pathogens of two species or sub-species, and 31 (2%) had ≥3 pathogens, species, or sub-species. Campylobacter (64%) was the pathogen most commonly detected in PDs, paired most often with Salmonella (38%), Shigella (22%), and Cryptosporidium (17%). Among persons with PDs, 1,204 (71%) were detected because one or both pathogens were detected by CIDTs. Among these test results, by person, 652 (54%) were solely PCR-based [381 (32%) syndrome panels, 271 (22%) laboratory-developed], 382 (32%) solely antigen- based, 91 (7%) unknown, and 79 (7%) multiple types. Average annual incidence rates of PDs increased 129% in 2015─2017 compared with 2011─2013 (0.71 vs. 0.31 per 100,000 persons). A reflex culture was performed on 403 (33%) of CIDT specimens with a PD; more than one pathogen was found in 42%, only one in 41%, and none in 17%. Conclusions: The number of PDs has increased dramatically with increasing use of CIDTs. More information on the sensitivity and specificity of CIDTs, initial culture, and reflex culture would help in making treatment decisions and informing interpretation of surveillance results. Presenter: Kelly Barrett, Centers for Disease Control and Prevention, Atlanta, GA, uzx2@cdc.gov The Recovery of Nontyphoidal Salmonella from CIDT-positive Stool Specimens K. Dillon, J. Hensley, A. Blackstock, E. Trees, J. Besser, H. Carleton, A. Huang and A. Williams-Newkirk, Centers for Disease Control and Prevention BEST POSTER 2019 Salmonella is estimated to cause 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths each year in the US. Clinical laboratories are adopting culture-independent diagnostic tests (CIDTs) to detect Salmonella and other pathogens in human stool. CIDTs are problematic for public health surveillance networks like PulseNet PublicHealthLabs @APHL APHL.org because they do not yield the isolates required for surveillance, subtyping, and outbreak detection. To maintain isolate availability, minimize costs, and improve turnaround time, an optimized, standard protocol for isolate recovery from CIDT-positive stool specimens is needed. This study examined the impact of transport media, transport temperature, plating media, and enrichment media on the recovery of two Salmonella serovars from human stool. Five stool samples from clinically healthy, anonymous donors were homogenized and pooled to make 1 standard stool, which was divided and spiked with either Salmonella enterica ser. Newport or Oranienburg at 104, 103, 102 and 101. The study was divided into 3 phases to address variables associated with isolate recovery and each phase. Within each phase, each combination of variables was tested in triplicate at each spike level. Phase 1 identified optimal transport temperature (4°C or 22°C), transport media (Cary-Blair Transport Medium or Gram-Negative broth), and plating media (Hektoen Enteric Agar or Xylose Lysine Deoxycholate Agar). Phase 2 assessed pathogen die-off in transit during warmer months and the effectiveness of ice mitigation (22°C, 22°C + ice, 55°C, 55°C + ice, and 78°C + ice). Phase 3 incorporated the results from the previous phases and identified an optimal enrichment (Modified Semi-Solid Rappaport Vassiliadis, Tetrathionate Broth, or Selenite Broth). For Phase 1, Salmonella was successfully recovered in 144/144 attempts from spiked stools held at 22°C, while only 61/144 recovery attempts were successful at 4°C. Recovery rates did not differ by serotype, transport time, plating media, or transport media. For Phase 2, Salmonella was successfully recovered in 144/144 attempts from spiked stools held at all transport temperatures except the 26/36 recovery attempts from those held at 55°C without ice. For Phase 3, Salmonella was successfully recovered in 270/270 attempts from spiked stools held in each enrichment. Results from this study strongly support the transport of Salmonella CIDT-positive stool specimens at 22°C to optimize isolate recovery, even at low pathogen loads. Specimens transported during the warmer months may need to be transported on ice while remaining at 22°C before and after transport. Enrichment has much less impact than transport temperature but may be necessary for specimens with low levels of Salmonella. Presenter: Katie Dillon, Centers for Disease Control and Prevention, Atlanta, GA, nev2@cdc.gov The Future of US National Cryptosporidiosis Surveillance: What Do 2016 NNDSS and CryptoNet Data Tell Us? A. Perez 1 , M. Hlavsa 1 , S. Gleason 1 , H. Seabolt 1 , J. Murphy 1 , S. Collier 1 , K. Fullerton 1 , L. Xiao 1 , D. Roellig 1 ; 1 Centers for Disease Control and Prevention, 2 South China Agricultural University Background: Cryptosporidium is the leading etiology of US recreational water–associated outbreaks and a leading cause of zoonotic outbreaks. At least 30 Cryptosporidium species have been identified. Outside the United States, select species have been associated with specific exposures. The species are generally indistinguishable by traditional diagnostic methods; only molecular methods can distinguish species. Cryptosporidium genotyping historically has been limited to outbreak investigations; National Notifiable Diseases Surveillance System (NNDSS) does not capture exposure data. CDC formally launched CryptoNet in mid-2015 to nationally and systematically collect genotyping and exposure data. This is the first examination of NNDSS and CryptoNet data together. Summer 2019 LAB MATTERS 51